The correct phrase is "blind in one eye", as it is the standard idiom used when referring to an individual who is blind in one eye. "In" is used to indicate where the disability is occurring.
Correct Sentence: He is blind in one eye. "In" indicates the specific area (the eye) affected.
Quick Info: If referring to being blind to a fault or truth, the phrase would be "blind to" (e.g., "He is blind to his own faults").